4.1. Resultados
4.1.3. Procedimientos para elaboración de la propuesta económica
The ultimate loads calculation, which is often required for certification calculations, is simple in concept: the results of a load case simulation are analysed to find the times at which each of a number of specified loads reaches its maximum and minimum values. The simultaneous values of all the loads at each of those instants is reported.
A further calculation named ‘ultimate load cases’ further analyses the results of a number of ultimate loads calculations for different groups of load cases, and generates a histogram showing the load cases in which the maximum and minimum values of each load occurred within each group.
9.9 Flicker
The Flicker calculation generates short-term flicker severity values (Pst), either from a voltage time history, or from time histories of active and reactive power. Such time histories are available from simulations with the full electrical model of the fixed speed induction generator, and also with the variable speed generator model.
The flicker severity is a measure of the annoyance created by voltage variations through perception of the resulting flicker of incandescent lights. The calculation of flicker from a voltage time history is defined in [9.5]. An algorithm conforming to this standard is incorporated into the Bladed post-processor. It can also calculate flicker from a time history of active and reactive power. In this case a voltage time history is calculated first, and this can be calculated for any given network impedance to which the wind turbine might be connected. In fact the flicker for several different network impedances can be calculated in a single calculation. The network impedances are entered as a set of short circuit power levels and network angles, the network angle being arctan(X/R), where X and R are the network reactance and resistance respectively. The voltage is calculated as the solution of the following equation:
U4+ U2(2{QX - PR} - U
02) + (QX - PR)2+ (PX + QR)2= 0
where U0 is the voltage at the infinite busbar, and P and Q are the active and reactive power respectively.
10. REFERENCES
2.1 Glauert H, “An aerodynamic theory of the airscrew”, Reports and memoranda, AE. 43, No 786, January 1922
2.2 Prandtl L and Tietjens O G, “Applied Hydro and Aeromechanics”, Dover Publications, 1957
2.3 Pitt D M and Peters D A, “Theoretical prediction of dynamic inflow derivatives”, Vertica, Vol. 5, No 1, 1981
2.4 Gaonkar G H, Sastry VV,, Reddy T S R, Nagabhushanam J and Peters D A, “The use of actuator disc dynamic inflow for helicopter flap lag stability”, 8th European Rotorcraft Forum, France, Sept. 1982
2.5 Tuckerman L B, “Inertia factors of ellipsoids for use in airship design”, NACA Report No 210, 1925
2.6 Rasmussen F R, Petersen S M, Larsen G, Kretz A and Andersen P D, “Investigations of aerodynamics, structural dynamics and fatigue on Danwin 180 kW”, Risø M-2727, June 1988
2.7 Snel H, Houwink R, Bosschers J, Piers W J and van Bussel G J W, “Sectional prediction of 3D effects for stalled flow on rotating blades and comparison with measurements”, EWEC ‘93, Travemunde, March 1993
2.8 Leishman J G and Beddoes T S, “A semi-empirical model for dynamic stall”, Journal of the American Helicopter Society, July 1989
2.9 Harris A, “The role of unsteady aerodynamics in vertical axis wind turbines”, Recent developments in the aerodynamics of wind turbines, BWEA workshop, University of Nottingham, February 1990
2.10 Galbraith R A McD, Niven A J and Coton F N, “Aspects of unsteady aerodynamics of wind turbines”, Recent developments in the aerodynamics of wind turbines, BWEA workshop, University of Nottingham, February 1990
4.1 Ahmed-Zaid S and Taleb M, Structural modelling of small and large induction generators using integral manifolds, IEEE trans. Energy Conversion 6, 3, September 1991.
4.2 Park R H, Two-reaction theory of synchronous machines, Trans AIEE 48, 1929. 4.3 Bossanyi E A, Investigation of torque control using a variable slip induction generator,
ETSU WN 6018, ETSU, 1991.
4.4 Pedersen T K, Semi-variable speed operation - a compromise? Wind Energy Conversion 1995, 17th BWEA Conference (Warwick), Mechanical Engineering Publications Ltd.
7.1 IEC 1400-1, Wind turbine generator systems - Part 1: Safety requirements, First edition, 1994-12.
7.2 Powles S R J, “The effects of tower shadow on the dynamics of a HAWT”, Wind Engineering, 7, 1, 1983.
7.3 Veers P S, “Three dimensional wind simulation”, SAND88 - 0152, Sandia National Laboratories, March 1988.
7.4 Engineering Sciences Data Unit, “Characteristics of atmospheric turbulence near the ground. Part II: Single point data for strong winds”, ESDU 74031, 1974.
7.5 Engineering Sciences Data Unit, “Characteristics of atmospheric turbulence near the ground. Part II: Single point data for strong winds (neutral atmosphere)”, ESDU 85020, 1985 (amended 1993).
7.6 Engineering Sciences Data Unit, “Characteristics of atmospheric turbulence near the ground. Part III: Variations in space and time for strong winds (neutral atmosphere)”, ESDU 86010, 1986 (amended 1991).
7.7 IEC 1400-1, Wind turbine generator systems - Part 1: Safety requirements, Second edition, 1997.
7.8 Ainslie J F, “Development of an eddy viscosity model for wind turbine wakes”, Proceedings of 7th BWEA Wind Energy Conference, Oxford 1985.
7.9 Ainslie J F, “Development of an Eddy Viscosity model of a Wind Turbine Wake”, CERL Memorandum TPRD/L/AP/0081/M83, 1983.
7.10 H Tennekes and J Lumley, “A first course in turbulence”, MIT Press, 1980. 7.11 L Prandtl, “Bemerkungen zur Theorie der freien Turbulenz”, ZAMM, 22(5), 1942. 7.12 Ainslie J F, “Calculating the flowfield in the wake of wind turbines”, Journal of Wind
Engineering and Industrial Aerodynamics, Vol 27, 1988.
7.13 Taylor G J, “Wake Measurements on the Nibe Wind Turbines in Denmark”, National Power, ETSU WN 5020, 1990.
7.14 Quarton D C and Ainslie J F, “Turbulence in Wind Turbine Wakes”, Wind Engineering, Vol. 14 No. 1, 1990.
7.15 U Hassan, “A Wind Tunnel Investigation of the Wake Structure within Small Wind Turbine Farms”, Department of Energy, E/5A/CON/5113/1890, 1992.
7.16 Vermeulen P and Builtjes P, “Mathematical Modelling of Wake Interaction in Wind Turbine Arrays, Part 1”, report TNO 81-01473, 1981.
7.17 Vermeulen P and Vijge J, “Mathematical Modelling of Wake Interaction in Wind Turbine Arrays, Part2”, report TNO 81-02834, 1981.
8.1 Goda Y, “A Review on Statistical Interpolation of Wave Data”, Report of the Port and Harbour Research Institute, Vol. 18, No. 1, March 1979.
8.2 Hogben N and Standing R, “Experience in Computing Wave Loads on Large Bodies”, OTC 2189, Offshore Technology Conference, Houston, 1975.
8.3 Wheeler J D, “Method for Calculating Forces Produced by Irregular Waves”, J. Petr. Techn., pp.359-367, March 1970.
8.4 Gudmestad O T, “Measured and Predicted Deep Water Wave Kinematics in Regular and Irregular Seas”, Marine Structures, Vol. 6, pp.1-73, 1993.
8.5 Chaplin J R, “The Computation of Non-Linear Waves on a Current of Arbitrary Non- Uniform Profile,” Den Report OTH 90 326, HMSO, 1990.
8.6 Dean R G, “Stream Function Representation of Nonlinear Ocean Waves,” Journal of Geophysical Research, Vol.70, No. 18, Sept. 1965.
8.7 Dean R G, “Stream Function Wave Theory: Validity and Application,” Proceedings of the Santa Barbara Specialty Conference, Ch. 12, Oct. 1965.
8.8 Dalrymple R A, “A Finite Amplitude Wave on a Linear Shear Current,” Journal of Geophysical Research, Vol. 79, pp. 4498-4504, 1974.
8.9 Dalrymple R A, “A Numerical Model for Periodic Finite Amplitude Waves on a Rotational Fluid,” Journal of Computational Physics, Vol. 24, pp. 29-42, 1977.
9.1 Rice S O, “Mathematical analysis of random noise”, Selected papers on noise and stochastic processes, ed. N Wax, 1959.
9.2 Davenport A G, “Note on the distribution of the largest value of a random function with application to gust loading”, Proc. Inst. Civil Eng. 28, pp187-196, 1964.
9.3 Madsen P H, Frandsen S, Holley W E, Hansen J C, “Dynamics and fatigue damage of wind turbine rotors during steady operation”, Risø report R-512, 1984.
9.4 Miner M A, “Cumulative damage in fatigue”, Transactions of the American Society of mechanical Engineers, Vol. 67, A159-A164, 1945.
9.5 Flickermeter functional and design specification, BSEN60868, 1993, and evaluation of flicker severity, BSEN60868-0, 1993, equivalent to IEC 868-0, 1991.